netdev - [PATCH net-next v3 17/23] eth: bnxt: adjust the fill level of agg queues with larger buffers

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Message-ID: <311f2a7b63a9ca20b0d0944657828093d05a5116.1755499376.git.asml.silence@gmail.com>
Date: Mon, 18 Aug 2025 14:57:33 +0100
From: Pavel Begunkov <asml.silence@...il.com>
To: Jakub Kicinski <kuba@...nel.org>,
	netdev@...r.kernel.org
Cc: asml.silence@...il.com,
	Eric Dumazet <edumazet@...gle.com>,
	Willem de Bruijn <willemb@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>,
	andrew+netdev@...n.ch,
	horms@...nel.org,
	davem@...emloft.net,
	sdf@...ichev.me,
	almasrymina@...gle.com,
	dw@...idwei.uk,
	michael.chan@...adcom.com,
	dtatulea@...dia.com,
	ap420073@...il.com,
	linux-kernel@...r.kernel.org,
	io-uring@...r.kernel.org
Subject: [PATCH net-next v3 17/23] eth: bnxt: adjust the fill level of agg queues with larger buffers

From: Jakub Kicinski <kuba@...nel.org>

The driver tries to provision more agg buffers than header buffers
since multiple agg segments can reuse the same header. The calculation
/ heuristic tries to provide enough pages for 65k of data for each header
(or 4 frags per header if the result is too big). This calculation is
currently global to the adapter. If we increase the buffer sizes 8x
we don't want 8x the amount of memory sitting on the rings.
Luckily we don't have to fill the rings completely, adjust
the fill level dynamically in case particular queue has buffers
larger than the global size.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
[pavel: rebase on top of agg_size_fac, assert agg_size_fac]
Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 28 +++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 50f663777843..b47b95631a33 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -3811,16 +3811,34 @@ static void bnxt_free_rx_rings(struct bnxt *bp)
 	}
 }
 
+static int bnxt_rx_agg_ring_fill_level(struct bnxt *bp,
+				       struct bnxt_rx_ring_info *rxr)
+{
+	/* User may have chosen larger than default rx_page_size,
+	 * we keep the ring sizes uniform and also want uniform amount
+	 * of bytes consumed per ring, so cap how much of the rings we fill.
+	 */
+	int fill_level = bp->rx_agg_ring_size;
+
+	if (rxr->rx_page_size > bp->rx_page_size)
+		fill_level /= rxr->rx_page_size / bp->rx_page_size;
+
+	return fill_level;
+}
+
 static int bnxt_alloc_rx_page_pool(struct bnxt *bp,
 				   struct bnxt_rx_ring_info *rxr,
 				   int numa_node)
 {
-	const unsigned int agg_size_fac = PAGE_SIZE / BNXT_RX_PAGE_SIZE;
+	unsigned int agg_size_fac = rxr->rx_page_size / BNXT_RX_PAGE_SIZE;
 	const unsigned int rx_size_fac = PAGE_SIZE / SZ_4K;
 	struct page_pool_params pp = { 0 };
 	struct page_pool *pool;
 
-	pp.pool_size = bp->rx_agg_ring_size / agg_size_fac;
+	if (WARN_ON_ONCE(agg_size_fac == 0))
+		agg_size_fac = 1;
+
+	pp.pool_size = bnxt_rx_agg_ring_fill_level(bp, rxr) / agg_size_fac;
 	if (BNXT_RX_PAGE_MODE(bp))
 		pp.pool_size += bp->rx_ring_size / rx_size_fac;
 
@@ -4396,11 +4414,13 @@ static void bnxt_alloc_one_rx_ring_netmem(struct bnxt *bp,
 					  struct bnxt_rx_ring_info *rxr,
 					  int ring_nr)
 {
+	int fill_level, i;
 	u32 prod;
-	int i;
+
+	fill_level = bnxt_rx_agg_ring_fill_level(bp, rxr);
 
 	prod = rxr->rx_agg_prod;
-	for (i = 0; i < bp->rx_agg_ring_size; i++) {
+	for (i = 0; i < fill_level; i++) {
 		if (bnxt_alloc_rx_netmem(bp, rxr, prod, GFP_KERNEL)) {
 			netdev_warn(bp->dev, "init'ed rx ring %d with %d/%d pages only\n",
 				    ring_nr, i, bp->rx_ring_size);
-- 
2.49.0